Dynamic characterization measurement of the circular foil heat flux sensor based on laser method

In order to make the circular foil heat flux sensor meet the growing demand for dynamic heat flux monitoring in extreme environments such as hypersonic wind tunnels, a dynamic calibration platform with a high-power semiconductor laser as heat flux source is built. Combining Finite Element Analysis (FEA) and experiments to carry out relevant studies. Our findings indicate a negative correlation between the time constant and laser power/pulse width, whereas the rise time is positively correlated with the laser pulse width. And they are all positively correlated with the coating thickness. Importantly, FEA revealed the independence of laser parameters from the time constant. Additionally, when the laser pulse width is approximately one order of magnitude less than the time constant of the sensor, it can be deemed an ideal pulse excitation. In the experiment, the maximum heat flow density was applied up to 3.49 MW/m², the minimum ideal pulse laser width can reach 1ms, the minimum time constant was measured to be 63 ms, and the minimum rise time was 12 ms. This research serves as a valuable reference for dynamically calibrating sensors using the laser method.